Production of colored photographs



Mama@ sepa, 1255; 392% W. F. FOX

PRODUCTION OF COLORED PHOTOGRAPHS mie@ June 22, 1920 ggz @afg

Patented Sept. Z5, 1928.

maaar ai Astetig? are WILLIAM FRANCIS FOX, OF NEW YORK, N. Y., ASSIGNOR TO NATURAL COLOR PIG- TURES COMPANY, INC., OF NEW`YORK,

N. 'YmA CORPORATION 0F DELAWARE.

PRODU'IION 0F GQLORIEIDf PHOTOGRAPHS.

Application filed .Tune 22,

My invention relates to a process for the production of positives in color, applicable to cinematography or still photography. It

also relates to a novel form of colored photoraphs, or series of such colored photographs or use in cinematography, or projection, as articles of manufacture.-

In accordance with my invention a base formed of transparent or translucent matelo rial is coated with a sensitive emulsion, which should be thicker than the usual emulsion used in blackand white photography. Images n alignment with each other-are printed on th s single coating of emulsion, one of such images being formed lon or adjacent to the rear surface of the emulsion, theother image being formed on the front or outer surface of the emulsion. These images being suitably colored there will result a composite image which may be in approximately natural `colors, formed by a pair of aligned images carried by a single coating of gelatin or other emulsion material upon one side of a suitable light-transmissive base. The emulsion may contain a coloring material, preferably a water-soluble yellow dye, adapted to prevent the actinic light-rays from penetrating entirely through the emulsion. The image which is formed on or adjacent to the under surface of the emulsion coating is printed through the base, the soluble dye which was carriedby the emulsion being subsequently removed.

In my application entitled Improvements in color photography, Serial V Number 390,902, tiled on even date herewith, the process briefly referred Vto above, is claimed in its broad aspect and the product formed thereby is also broadly claimed. In the present ap- 40 plication a process will be claimed which is specifically diii'erent from that specifically described and claimed in my said co-pending application. I will also claim herein a form of product which is different from that specifically described in my said co-pending application.

In my ,said'co-pending application positive images are printed in alignment on the upper and under surfaces of the single emulsion coating in alignment with cach other, which images may be printed'from negatives ofthe same object taken through complementary color screens. The film is toned, or vmordanted and dyed to a color suitable for the under image, afterwhich the clear gelatin is 1920. Serial N0. 390,901.

which is printed in alignment therewith on the upper surface of the emulsion is, however, a negative image, corresponding to the other of Ithe two negatives taken through the complementary color screens. The film is then toned to a color appropriate to the under image and the gelatin is at the same time hardened in proportion to the amount of tone.

The film is now subjected tothe action of an acid dye bath, of a color complementary to that which Was produced by the toning. This will act most vigorously7 on the lsoft portions of the film and less vigorously on the hardened portions. This dyeing operation will. color the parts of the top image which were white, and will change the parts of the top image which were of the color of the toning-batln--to white. The result of this treatment'will be to change the top image to a posi'- 'tive representation of the color elements which passed through the color screen fromwhich the negative corresponding to the top image was taken.

Attention is hereby directed to the accompanying drawings forming part of this application and illustrating diagrammatically my improved process. In the drawings Fig. Y1 represents a portion of a single coated film orI base having a positive image 'formed on the under side of the emulsion coating, l'the latter ,being shown part-ly separated from the base, for purposes of illustration, Fig. 2 shows the same portion of film within a negative image formed on the upper surface of the emulsion in registry with the under image, Fig. 3 represents the same portion of film with designation of the first coloring step i and the hardening of the emulsion, Fig. .4

represents the same portion of film with designation thereon of the final color step, and Fig. 5 shows the same portion of film with the negative image formed on the upper sur` face of the emulsion through -a line screen.

Procding now to a more detailed description of my present process, the latter may be referred to as a two-colorprocess in which the negatives are made In the usualway, one

the red screen. The two screens are, in fact,

complementary,'the`term red and greenA being used to readily distinguish the one from the other."

Having obtained the negatives, the positives may be formed in the following manner A transparenter translucent base 1 is coated with a suitablesensitive emulsion 3 of any usual character suitablefor color photography, on one side of the base only. The base may be formed o-f the usual pyro-xylin film stock used in cinematography, Aor, the like, or glass if desired, for still photography. A dye is incorporated in the emulsion suitable to preventA actinic light-rays penetrating through the body of the emulsion when the images areprinted from opposite sides of the lm. I have found a. yellow dye is well adapted Jfor this purpose, tartrazine being particularly suitable. This dye is water-soluble so that in the operations of developing and treating the emulsion it will wash out of the gelatin,

or otheremulsion material used. This coatin' of emulsion, as stated above,`is somewhat thicker than the usual emulsion used in blackl and white photography since a portion of the same must separate" the two images in alignment. l i

i A print is made from' oneof the negatives, the image being printed throughthe light- Y` 'ftrainissivebase 1, upon the under side 2 of ed from this positive.

the emulsion coat-ing Y3*, so that the impressed.

or front side Llof the emulsion. This printed image when developed will be a positive representation 5 -of certain color values of the picture. As an example of my process it may be assumed that this print is made from the` tion 6 of the red values of the picture, in the example referred to. Thistop negative image 6 will be obtained from a positive print which Amay be made in the ordinary way, obtainedfrom the negativetaken'through the green filter, the image on the emulsion being print- The two impressed images 5 and 6 are now image doesrnot penetrate through to the top-I developed in the ordinary developer, fixed silver originally present in the image, the

penetration of an acid dye. A suitable toning bath made up of Vanadium chloride 20 .grains Ferrie ammonium oxalate 10 grains Ferrie chloride l0 grains Potassium ferricyanide 20- grains Glacial acetic acid 10 minims Oxalic acid 100 grains Suiiicient water to make total Dcomposition 100 y ounces.` i

After toning, as describe-d, the film is now immersed in a suitable clearing bath,vwhich may be a sodium thiosulphate bath, and is then washed and dried. vWe now have a film the gelatin coating of which contains two im-\ ages 5 and 6, b'oth colored "greenas at 7,'the

yellow dye having been previously washed out of the gelatin. The bottom image, the one that was printed through 'the base, will remain green in the finished print, but the top y image must be changed over to a lred color as at 8 V(see Fig. 4)'. `The top image is a negative', so that the parts of the original object photographed which were white are green in this toned image, and the parts which were red inl the original object are clear gelatin. ln toning this negative image to a green color the gelatin was hardened pro rata to the amount of toning so that in the clear portions ofthe film the gelatin is soft, and in the parts, where there is a large amount of green color the gelatin is hard. It is well known thatif certain green tones are stained with a red dye, the dye will enter the film to a limited extent, changing over the color of the tone practically to white. This can readily be done providing the printing and developing of the original image has not been carried too far since if the tone is too heavy the dye will not penetrate the film at all. l

In practicing my invention the toning is carried out to such an extent as to allow as nearly a perfect white as possible with the maximum quantity of red dye in the clear portion of the gelatin. The film now being immersed in a suitable acid red dyeing bath, the dye will act most vigorously on the soft' portions of the film and less vigorously on the hardened port-ions. Thisv will convert the negativeimage of the red impressions to a positive image of the red'as seen in the ori nal object photographed. The parts of tlxe ess described since the clear the white image of the simplest way is -to make 1 printing and use this for .imageg' Another method is `broken up the better to allow upper image which were of a green color will now be white or approximately so andthe parts of the image which were white will be of a full red. Thus are obtained a red and a green image in the one coat of emulsion material, as the under image will not be affected by the dye, the top image preventing penetration of the dye to any parts of the under image where the dye should not go.

Various acid red dyes may be used in practicing the process.l

Full reds will easily be obtained in the procgelatin in the two images will not be hardened, thus allowing the dye to penetrate tothe full thickness of the gelatin. Greens will be obtaine'dby the 'green in the under image being seen through top print. Whites will be clear gelatin'in the underimage protected by the tone in thetop. been converted to white by-action of the dye. Blacks will be obtained by the under image having a full green, while the top image has an aligned portion clear gelatin has been dyed to afull red and so on through the scale of colors'` obtainable.

In printing the top image on the emulsion it may be found better to use a line screen, or a screen composed of dots, in order to obtain .a better quality of white. This screen may be similar to the ones used in half tone process work and will split up the at 49 (see Fig. 5) so thattlie dye will be better able to combine With the green tone in order to form white. This line screen may be -interposed in any position between the printwhich t-he negative is ing positive, -from printed'on the top of the emulsion, and the emulsion, so that the resultant image will be the action of the dye. While the use of such sometimes be of advantage in making the top image, it will not benecessary in printing t e under image. y

To yobtain the positive for printing the top image, many methods may be employed. The a positive by contact 'printing the top to chemically reverse the green negative before fixing the same in one ofthe many well known reversing baths such as one containing potassium permanganateand sulphuric acid. i

In cinematography, where a continuous series of pictures is required to be printed, and shrinkage of the negative is to be taken into consideration, a so-ealled dupe or secondary printing negative may be made, consisting of an alternate negative image and positive image. A negative image of the object photographed through the red filter and a positive image of the object photographed through the green filter would then appear side by side on the same length of the film, or

alternately in a straight line sequence, if deimage, whlch tone has of surface in which thel top image as shown `sion separating said images,

In cinematography, if the -red and green Apictures alternate in straight line sequence in the original negative, a special. form of4 printing machine will have to be used in order to obtain the proper sequence of the prints with `all the'red prints in straight line sequence on one side of' the emulsion coating and all of the green prints in alignment therewith on the opposite side-of the emulsion coating. Suitable apparatus may be obtained for 'this purpose and is, of course,

no part of my present invention. In taking the original. negatives,

however, two negative strips -may be taken side by side one vthrough a green filter and one through ared filter and one of these strips converted to a positive'after which the two separatestrips may be used for printing. In this case a specially designed printer would' notl be required provided that the mechanism of ,the prlnter were accurate. l The film should be immersed in a suitable as stated, until the whites acid red dye bath, show up pure white after which'the-lm vmay and dried. It is be rinsed in clear Water then ready for projection.

, It should be understood that the tion given above, madefrom the negative taken through the red filter and the upper print corresponds/to the negative taken through the green filter, is given by away of example and not by way of limitation of my invention. This process may be reversed, the under print being descriplmade from the. negative taken through the greenfilter and the film toned in a suitable red toning is printed from a postive made from a negative taken through the red filter, a suitable green acid dye being then used for the final coloring step.

What I claim'is-z l. A 'photographic process comprising, printing image of the same object in alignment in a single coating of sensitive emulsion on one side of a suitable base, with unaffected emulsaid positive image being undermost, toning both images one color and-hardening the emulsion material in proportion to the amount of tone, and dyeing the film With a dye of a second color, adapted to act vmost vigorously on the soft portions of the film.v 2. A photographic process comprising,

in which the under print is a positive image and a 'negative los printing a positive image and a negative y negative print having complementary color.

' side of a suitable base, with unaffected emulsion separating said images, said positive image being undermost, said positive print being made from a negative from which green Color sensations are omitted and said negative print having red color Vs ensations omitted therefrom, toning both images green, and hardening'the emulsion material in proportion to the amount of tone, and dyeing the filmwith a red acid dye, said dye acting most vi orously on the unhardened portions 0f the lm, and converting the parts of the i' i upper image which were green to white.

4. A photographic process, comprising printing a positive image through alight transmissive base on the under surface'of a coat of sensitive emulsion on the other side ofthe base, from a negative from which cer-` tain color sensations have been omitted, the emulsion being so treated as to prevent the actinic light rays from penetrating entirely through the emulsion, printing a negative image of the same object, from which color sensations are omitted, different from those omitted from the negative first mentioned, on the upper surface of said'emulsion coating, in alignment with said positive image,

developing, fixing,- toning the film to a desired color, and hardening the emulsion material in proportion to the amount of tone, and

dyeing the film with a dye of a second color,

L dyed image,

adapted to act most vigorously on the soft portions of the film.

' 5. A photographic process, comprising printing a positive image through a light transmissive base on the under surface of a coat of sensitive emulsion on the other side of the base, from a negative from which certain color sensations have been omitted, the emulsion being so treated as to preventdthe actinic light rays from penetrating entirely through the emulsion, printing a negative image of the same object', from which color sensations are omitted, complementary to those omitted from the negative first mentioned, onthe upper surface of said emulsion coating, in alignment with said positive image, developing, fixing, color corresponding to the color values of said positive print and hardening the emulsion material in proportion to the amount of tone and dyeing the film with an acid dye of acolor complementary to that imparted by the toning, said dye being adapted to act most vigorously on the unhardened portions of the film.

6. As a new article of manufacture, a light "transmissive base having a Coating of emulsion material on one side, with two images of the same ob]ect fo-rmed therein in alignment', one of the same being a negative image,

and the other formed on the under surface of said coating, being a positive image.

7 As a new article of manufacture, a light-transmissive base having a coating of emulsion material on one side, with two images of the same object formed therein in alignment, one of the same being a toned image, formed on the under surface of said coating, representing certain color values of the object photographed, and the other being color values of the object photographed.

This specification signed and witnessed this 1st day of J une, 1920.

' WILLIAM FRANCIS FOX.

toning the film to a representing complementary 

